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  1. using System;
  2. using System.Linq;
  3.  
  4. public class Program
  5. {
  6.     public static void Main()
  7.     {
  8.         const int N = 5, K = 3;
  9.  
  10.         // 1 represents +, 0 represents -
  11.         var results =
  12.             Enumerable.Range(0, 1 << N)
  13.                 .Select(bits =>
  14.                 {
  15.                     var permutation =
  16.                         Enumerable.Range(0, N)
  17.                             .Select(n => ((bits & (1 << n)) != 0) ? (n + 1) : -(n + 1))
  18.                             .ToList();
  19.  
  20.                     var sum = permutation.Sum();
  21.                     var str = string.Join(" + ", permutation);
  22.  
  23.                     return new {sum, str};
  24.                 })
  25.                 .Where(intermediate => intermediate.sum == K)
  26.                 .Select(intermediate => $"{intermediate.str} = {K}");
  27.  
  28.         Console.WriteLine(string.Join("\n", results));
  29.     }
  30. }
  31.  
Success #stdin #stdout 0.02s 17572KB
comments (?)
stdin 
Standard input is empty
stdout 
-1 + 2 + 3 + 4 + -5 = 3
1 + -2 + 3 + -4 + 5 = 3
-1 + -2 + -3 + 4 + 5 = 3
https://ideone.com/Z7NvZI
language:
C# (gmcs 5.20.1)
created:
3 years ago
visibility:
public

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